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Am Fam Physician. 2013;88(9):608-609

Clinical Question

Does penicillin in a low dose prevent recurrent cellulitis of the leg?

Bottom Line

For patients with at least two previous episodes of cellulitis in the previous three years, low-dose penicillin can prevent recurrence (number needed to treat = 6). (Level of Evidence = 1b)


Patients with at least two episodes of leg cellulitis within the past three years were eligible for the study. The mean age was 58 years, 60% were women, the mean body mass index was 35 kg per m2, and 25% had venous insufficiency. The average number of previous episodes of cellulitis was 3.75. Patients were randomized to receive 250 mg of penicillin twice daily or placebo, and groups were balanced at the start of the study. Although 274 patients were initially randomized, 26 withdrew consent, were lost to follow-up, or died. Patients were followed for at least 18 months and up to three years. At the end of the follow-up period, the median time to the first recurrent episode of cellulitis was 626 days for those receiving penicillin and 532 days for those receiving placebo. The probability of any recurrence was lower in those receiving penicillin (22% vs. 37%; P = .01; number needed to treat = 6). Adverse events were slightly less common in the penicillin group and were mild. Patients with a higher body mass index, those with edema, and those with more previous episodes were less likely to respond.

Study Information

Study design: Randomized controlled trial (double-blinded)

Allocation: Concealed

Setting: Inpatient (any location) with outpatient follow-up

Funding source: Foundation

Reference: ThomasKSCrookAMNunnAJet alU.K. Dermatology Clinical Trials Network's PATCH I Trial TeamPenicillin to prevent recurrent leg cellulitis. N Engl J Med. 2013; 368( 18): 1695– 1703.

POEMs (patient-oriented evidence that matters) are provided by Essential Evidence Plus, a point-of-care clinical decision support system published by Wiley-Blackwell. For more information, see Copyright Wiley-Blackwell. Used with permission.

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